Linked List (Time Complexity)

Question

What would be the asymptotic time complexity to add a node at the end of singly linked list, if the pointer is initially pointing to the head of the list?

1. O(n)
2. O(1)
3. θ(n²)
4. θ(n)

Comments

both O(n) and θ(n) are correct.

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Okay! i don't know why, but the answer key go with θ(n).

But i also clearly agree with both the options.

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I think in general it should be O(n) as best case is O(1) answorst is O(n). But the question specifies that we have to add a node at last when the pointer is initially at start. So in best case and worst case both it comes O(n) that's why the answer is Theta(n).

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in any case, you need to reach the last node to insert new node  so it cant be done by traversing  less than n nodes.so theta(n) is correct

Answer 1

Answer would be 4- theta(n)

However o(n) is also possible but most appropriate will be theta(n)  because here on both worst and best case we have to traverse at the end of list to add the new node..